1. Field of the Invention
The present invention concerns a method for fabricating a hearing aid shell and a mold from which a hearing aid will be produced, that allow a test fitting by a user (wearer) of the hearing aid before the final hearing aid device is manufactured.
2. Description of the Prior Art
Hearing-impaired patients often reject a hearing aid device due to a poor fit. This results in longer patient care cycles while re-manufacturing the device in order to put it in a form that the patient will find acceptable. Returns to the factory or manufacturing facility also create waste and additional costs that could be avoided if the initial device achieved a satisfactory (comfortable) fit in the ear canal of the hearing-impaired person.
The primary reason for such factory returns is that patient acceptance, which is normally based on a comfortable and stable fit in the ear canal, can be verified with certainty only after the finished device is manufactured and shipped back to the dispenser site, when for the first time it is placed in the ear canal of the patient.
The conventional procedure for producing a hearing aid with a fit that is comfortable for the patient is schematically illustrated in FIG. 1. As shown in FIG. 1, the patient visits a dispenser (retail) location, and is examined by an audiologist. Appropriate procedures are performed to determine the hearing impairment of the patient, referred to in general as production of an audiogram. From this, the required features of the hearing aid device are determined, such as the amplification power, the frequency response, special programs for particular audio environments, etc. Based on all of this information, the audiologist recommends a suitable hearing aid type. Another factor which may enter into this determination is a preference on the part of the patient for a hearing aid having the smallest possible size.
Audiologists generally have different hearing aids available for demonstration purposes. These are typically built to the dimensions and shape of the audiologist's ear. The patients can hold and examine these actual items, but the patients cannot determine exactly how the hearing aid will feel in the patient's own ear, because the demonstration sample was manufactured for a different individual.
For customizing the shape of the hearing aid device to the patient's ear, the audiologist makes a mold of the patient's ear, including the auditory canal, using quick hardening foam. For this purpose, foam is introduced into the ear of the patient, and hardens therein in a few minutes. The mold is then removed using a string connected to a plug at the distal end of the mold. The mold provides an impression of the patient's ear canal.
The patient's ear mold and hearing aid requirements are then physically sent to a manufacturing site for producing a customized hearing aid for that particular patient. The transfer to the manufacturing site usually takes place by ground shipping, which requires several days. At the manufacturing site, the hearing aid device, customized for fitting into the ear canal of the patient, commonly called an otoplastic, is manufactured based on the mold, and the appropriate electronic components, customized to compensate for the particular hearing impairment of the patient, are placed in the device. The manufactured hearing aid is then returned to the audiologist, again usually by a ground carrier.
The patient then schedules another visit to the audiologist for fitting of the hearing aid. Often the hearing aid provided by the manufacturer does not feel comfortable to the patient, or does not produce a satisfactory correction of the hearing impairment of the patient. Sometimes the unacceptability of the hearing aid is due to tolerances or imperfections in the manufacturing procedure, but it is also possible that the mold could shrink or become slightly deformed due to environmental changes such as temperature or pressure or mishandling, so that the hearing aid device produced from this mold embodies those changes, and therefore is not acceptable to the patient. Sometimes the necessary changes are relatively minor, and can be done by the audiologist, but often the changes that are necessary to make the hearing aid acceptable to the patient to the patient require that the hearing aid be returned to the manufacturer at the fabrication site. Sometimes the hearing aid can be modified and still used, but in other instances the manufacturing procedure must be done again.
In any event, the first time that the patient has an opportunity to experience a test fitting of the device is after the device has already been manufactured. Sometimes, multiple iterations may be necessary in order to achieve a fitting and hearing impairment correction that are satisfactory to the patient. Each iteration may require modifications to the mold, returning it to the fabrication site, manufacturing a new otoplastic and installing new electronic components therein, and assembly and testing of the finished device, as well as shipping it back to the location of the audiologist, and again scheduling another visit at the audiologist with the patient.